Barrier coated thermo-mechanically stable, heat sealable film, a packaging laminate comprising the film, a packaging container formed from the packaging laminate and a method for the production of the film

Abstract

The invention relates to a thermo-mechanically stable, heat sealable vapour deposition barrier-coated polymer film, substantially comprising polymers based on polyethylene. The invention especially relates to such a metallised polymer film. The invention also relates to a packaging laminate comprising the vapour deposition coated polymer film and to a packaging container produced from such a packaging laminate. The invention further relates to a method for the production of the coated, stable, heat sealable polymer film and to the method of manufacturing a packaging laminate including the heat sealable film.

1 . A thermo-mechanically stable, heat sealable, polymer film, suitable for liquid carton lamination and heat-seal packaging, comprising a core layer consisting of polyethylene and comprising more than 40 weight-% of a polyethylene selected from the group consisting of MDPE, HDPE, modified MDPE, modified HDPE, and blends of two or more thereof, the film further having a heat sealing layer, which is contiguous to the core layer on a first side and consists of low density ethylene polymer, and having a thin vapour deposition barrier coating on its second, opposite side, the polymer film having a total thickness of from 12 to 20 μm, preferably from 14 to 18 μm. 
     
     
         2 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the thin vapour deposition coating is a layer of metal or metal oxide. 
     
     
         3 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the core layer further has a coating-receiving layer, applied in contiguous contact with its second, opposite, side, underneath the vapour deposition coating, also consisting of polyethylene, for receiving the vapour deposition coating layer. 
     
     
         4 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the heat sealing layer comprises mainly low density ethylene polymers selected from the group consisting of LDPE, LLDPE, metallocene-catalysed LLDPE and blends of two or more thereof. 
     
     
         5 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the film is a blown film manufactured by film blowing technology and subsequent vapour deposition coating. 
     
     
         6 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in as claimed in  claim 1 , wherein the coating receiving layer comprises in the majority a polymer selected from a group consisting of LDPE, linear low density polyethylenes, metallocene-catalysed ethylene polymers and ethylene-propylene ter-co-polymers with a third, alpha-olefin monomer. 
     
     
         7 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 6 , wherein the metallocene-catalysed ethylene polymer is selected from the group consisting of m-LLDPE, m-HDPE and m-MDPE. 
     
     
         8 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 7 , wherein the metallocene-catalysed polyethylene is blended with a non-metallocene-catalysed polyethylene within the same density category. 
     
     
         9 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 8 , wherein the metal receiving layer comprises a blend of m-HDPE and HDPE. 
     
     
         10 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in as claimed in  claim 1 , wherein the metal receiving layer comprises a polyethylene selected from the group consisting of LDPE, linear low density polyethylenes and blends of two or more thereof. 
     
     
         11 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the core layer in itself is a multilayer structure with layers of the same or similar polyethylene or polyethylene blend. 
     
     
         12 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 2 , wherein the metallised layer has an optical density (OD) of from 1.8 to 3.0. 
     
     
         13 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 2 , wherein the metallised layer has an adhesion of at least 200 N/m. 
     
     
         14 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the film has an oxygen transmission rate lower than 100 cm 3 /(m 2 *24 h), 1 atm O 2 , 23° C., 50% RH. 
     
     
         15 . A thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , wherein the film has a water vapour permeation rate of lower than 5 g/m 2  at 38, and 23, ° C., 24 hours, at a gradient of from 0 to 90% RH. 
     
     
         16 . A packaging laminate comprising a film, according to  claim 1 . 
     
     
         17 . A packaging laminate according to  claim 16 , also comprising a paper or paperboard core layer. 
     
     
         18 . A packaging laminate according to  claim 16 , wherein said heat sealable polymer film forms a surface of the packaging laminate intended to form an interior surface of a package made from said packaging laminate. 
     
     
         19 . A packaging laminate according to  claim 16 , wherein a further oxygen barrier layer is arranged between the paperboard and the heat sealable polymer film. 
     
     
         20 . A liquid packaging container formed from a packaging laminate according to  claim 16 . 
     
     
         21 . A method for the manufacturing of the barrier coated, thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 1 , which method comprises the steps of:
 a) forming a polymer film at a thickness of from 12 to 20 μm, preferably from 14 to 18 μm, by means of an extrusion manufacturing method, the polymer film comprising a core layer consisting of polyethylene, and comprising more than 40 weight-% of a polyethylene selected from the group consisting of MDPE, HDPE, modified MDPE, modified HDPE and blends of two or more thereof, the polymer film further comprising a heat sealing layer, which is laminated to the core layer on a first side and which consists of low density polyethylene, and subsequently   b) vapour depositing (40) a barrier coating onto the other, second side of the film.   
     
     
         22 . A method for the manufacturing of a barrier coated, thermo-mechanically stable, heat sealable, polymer film, as claimed in  claim 21 , which method further comprises:
 c) surface treating the second side of the polymer film to be vapour deposition coated, before the step b) of vapour depositing the barrier coating.   
     
     
         23 . A method according to  claim 21 , wherein the vapour deposition coated layer is a metallised layer. 
     
     
         24 . A method according to  claim 23 , wherein the metallised layer is vapour deposited to an optical density of from 1.8 to 3.0. 
     
     
         25 . A method according to  claim 21 , wherein the polymer film has a coating-receiving layer towards the vapour deposition coated layer. 
     
     
         26 . A method according to  claim 25 , wherein the receiving layer is surface treated in a step c) before the step b) of vapour depositing the barrier coating.